Curable composition

ABSTRACT

Provided are a curable composition and its use. The curable composition may provide a cured product having excellent processability and workability, no surface stickiness, and an excellent adhesive property. The curable composition has excellent thermal resistance, crack resistance, and gas permeability. The curable composition may have stable performance when being applied to a semiconductor device at a high temperature for a long time.

FIELD

The present application relates to a curable composition and its use.

BACKGROUND

A light-emitting diode (LED) is a diode used in various fields such as alight source of a display device and lighting.

As an LED encapsulant, an epoxy resin having a high adhesive propertyand excellent mechanical durability is being widely used. However, theepoxy resin has lower light transmittance of a blue light or UV rayregion, and low thermal resistance and light resistance. Accordingly,for example, the patent documents 1 to 3 disclose techniques for solvingthe above-described problems. However, encapsulants disclosed in theabove references do not have sufficient thermal resistance and lightresistance.

In addition, to maintain stable performance under various and harshconditions in which LEDs are encountered, a material having excellenttransparency, initial speed of light, high temperature thermalresistance, thermal and impact resistance, and gas permeability isdemanded.

PRIOR ART DOCUMENTS

-   PATENT DOCUMENT 1: Japanese Laid-Open Patent Application No.    H11-274571-   PATENT DOCUMENT 2: Japanese Laid-Open Patent Application No.    2001-196151-   PATENT DOCUMENT 3: Japanese Laid-Open Patent Application No.    2002-226551

DESCRIPTION Object

The present application provides a curable composition and its use.

Solution

One aspect of the present application provides a curable compositionincluding components that can be cured by hydrosilylation, for example,a reaction between an aliphatic unsaturated bond and a hydrogen atombinding to a silicon atom. For example, the curable composition mayinclude a polyorganosiloxane including an aliphatic unsaturated bond anda polyorganosiloxane including a hydrogen atom binding to a siliconatom.

The term “M unit” used herein may refer to a monofunctional siloxaneunit possibly represented by the formula of R₃SiO_(1/2) in the field ofart, and the term “D unit” used herein may refer to a bifunctionalsiloxane unit possibly represented by the formula of R₂SiO_(2/2) in thefield of art, the term “T unit” used herein may refer to a trifunctionalsiloxane unit possibly represented by the formula of RSiO_(3/2) in thefield of art, and the term “Q unit” used herein may refer to atetrafunctional siloxane unit possibly represented by the formula ofSiO_(4/2). Here, R is a functional group binding to a silicon (Si) atom,and may be, for example, a hydrogen atom, an epoxy group, or amonovalent hydrocarbon group.

The curable composition may include a polyorganosiloxane (hereinafter,referred to as a polyorganosiloxane (A)) including an aliphaticunsaturated bond, for example, a crosslinked polyorganosiloxane. Theterm “crosslinked polyorganosiloxane” used herein may refer to apolyorganosiloxane, which essentially includes a T or Q unit, and has aratio (D/(D+T+Q)) of a number of moles of a D unit to the D, T, and Qunits included in the polyorganosiloxane of less than 0.7, 0.65 or less,0.6 or less, 0.5 or less, 0.4 or less, or 0.3 or less. The lower limitof the ratio (D/(D+T+Q)) of the number of moles of the crosslinkedpolyorganosiloxane is not particularly limited, and for example, may be0.

The polyorganosiloxane (A) may be a low-refractive-indexpolyorganosiloxane. The term “low-refractive-index polyorganosiloxane”used herein may be a polyorganosiloxane including an aryl group in amolecule with a small amount, or substantially excluding an acryl group.For example, herein, the low-refractive-index polyorganosiloxane may bea polyorganosiloxane having a molar ratio (Ar/Si) of an aryl (Ar) groupto total silicon (Si) atoms of the polyorganosiloxane of 0.3 or less,0.2 or less, approximately 0.15 or less, approximately 0.1 or less, orapproximately 0.06 or less, or substantially 0. On the contrary, theterm “high-refractive-index polyorganosiloxane” used herein may be apolyorganosiloxane including a predetermined ratio or more of arylgroups in a molecule. For example, the high-refractive-indexpolyorganosiloxane used herein may be a polyorganosiloxane having aratio of a number of moles of aryl (Ar) groups to total silicon (Si)atoms of the polyorganosiloxane of 0.25 or more, 0.3 or more, or 0.4 ormore. For the high-refractive-index polyorganosiloxane, the ratio(Ar/Si) may be 2.0 or less, 1.5 or less, 1 or less, or approximately 0.8or less. The term “aryl group” used herein may refer to, unlessparticularly defined otherwise, a monovalent residue derived from acompound having a structure to which a benzene ring or at least twobenzene rings are linked, or in which one or at least two carbon atomsare covalently condensed or connected or a derivative thereof. In thespecification, in the category of aryl groups, a functional groupconventionally referred to as an aryl group, and an aralkyl group orarylalkyl group may be included. The aryl group may be, for example, anaryl group having 6 to 25, 6 to 21, 6 to 18, or 6 to 12 carbon atoms.The aryl group may be a phenyl group, a dichlorophenyl group, achlorophenyl group, a phenylethyl group, a phenylpropyl group, a benzylgroup, a tolyl group, a xylyl group, or a naphthyl group.

When the polyorganosiloxane (A) is a low-refractive-indexpolyorganosiloxane, it may ensure physical properties includingexcellent transparency of a curable composition or a cured productthereof, and particularly, maintain very excellent thermal resistance ata high temperature.

The polyorganosiloxane (A) may have, for example, an average empiricalformula of Formula 1.

(R¹ ₃SiO_(1/2))_(a)(R²₂SiO_(2/2))_(b)(R³SiO_(3/2))_(c)(SiO_(4/2))_(d)(OR)_(e)  [Formula 1]

In Formula 1, R and R¹ to R³ may be each independently a monovalenthydrocarbon group, at least one of R¹ to R³ may be an alkenyl group, andeach of a, b, c, d, and e may be 0 or a positive number, d/(c+d) may be0.3 or more, and e/(c+d) may be 0.2 or less. However, at least one of cand d may be a positive number. When the polyorganosiloxane (A) is alow-refractive-index polyorganosiloxane not substantially including anacryl group, R and R¹ to R³ may be respectively the substituentexcluding an aryl group.

In the specification, the expression that the polyorganosiloxane has aspecific average empirical formula may mean that the polyorganosiloxaneis composed of a single component represented by the average empiricalformula, or a mixture of at least two components, and an average of acomposition of the components of the mixture is represented by theaverage empirical formula.

In the specification, the term “epoxy group” used herein may refer to,unless particularly defined otherwise, a monovalent residue derived froma cyclic ether having three ring-forming atoms or a compound includingthe cyclic ether. The epoxy group may be a glycidyl group, an epoxyalkylgroup, a glycidoxyalkyl group, or an alicyclic epoxy group. Here, thealicylic epoxy group may include a monovalent residue derived from acompound including an aliphatic hydrocarbon ring structure, and astructure in which two carbon atoms forming the aliphatic hydrocarbonring also form an epoxy group. The alicyclic epoxy group may be analicyclic epoxy group having 6 to 12 carbon atoms, for example, a3,4-epoxycyclohexylethyl group.

The term “monovalent hydrocarbon group” used herein, unless particularlydefined otherwise, may refer to a monovalent residue derived from acompound composed of carbon and hydrogen, or a derivative thereof. Forexample, the monovalent hydrocarbon group may include 1 to 25 carbonatoms. The monovalent hydrocarbon group may be an alkyl group, analkenyl group, or an alkynyl group. In one example, the monovalenthydrocarbon group of Formula 1 may be selected from monovalenthydrocarbon groups excluding an aryl group.

The term “alkyl group” used herein may refer to, unless particularlydefined otherwise, an alkyl group having 1 to 20, 1 to 16, 1 to 12, 1 to8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched,or cyclic structure. In addition, the alkyl group may be arbitrarilysubstituted with at least one substituent.

The term “alkenyl group” used herein may refer to, unless particularlydefined otherwise, an alkenyl group having 2 to 20, 2 to 16, 2 to 12, 2to 8, or 2 to 4 carbon atoms. The alkenyl group may have a linear,branched, or cyclic structure, and may be arbitrarily substituted withat least one substituent.

The term “alkynyl group” used herein may refer to, unless particularlydefined otherwise, an alkynyl group having 2 to 20, 2 to 16, 2 to 12, 2to 8, or 2 to 4 carbon atoms. The alkynyl group may have a linear,branched, or cyclic structure, and may be arbitrarily substituted withat least one substituent.

As a substituent that may be arbitrarily substituted to an epoxy groupor a monovalent hydrocarbon group, a halogen such as chlorine orfluorine, a glycidyl group, an epoxyalkyl group, a glycidoxyalkyl group,an epoxy group such as an alicyclic epoxy group, an acryloyl group, amethacryloyl group, an isocyanate group, a thiol group, or a monovalenthydrocarbon group, but the present application is not limited thereto.

The polyorganosiloxane (A) is a low-refractive-index polyorganosiloxane,and thus the above-described molar ratio (Ar/Si) of an aryl group may be0.3 or less, 0.2 or less, approximately 0.15 or less, approximately 0.1or less, approximately 0.06 or less, or substantially 0. When thepolyorganosiloxane (A) is blended with a suitable high-refractive-indexpolyorganosiloxane, a cured product may maintain excellent thermalresistance at a high temperature.

In Formula 1, one or at least two of R¹ to R³ may be an alkenyl group.In one embodiment, the alkenyl group may be present in an amount suchthat the molar ratio (Ak/Si) of the alkenyl (Ak) group to total silicon(Si) atoms included in the polyorganosiloxane (A) is approximately 0.02to 0.5. The molar ratio (Ak/Si) may be, in another embodiment, 0.04 ormore or 0.06 or more. In addition, the molar ratio (Ak/Si) may be, inanother embodiment, 0.4 or less, 0.3 or less, or 0.2 or less.Accordingly, reactivity with another component such as apolyorganosiloxane (B) may be suitably maintained, a phenomenon ofleaking an unreacted component from a surface of the cured product maybe prevented, and excellent hardness, crack resistance, and thermal andimpact resistance of the cured product may be maintained.

In the average empirical formula of Formula 1, a, b, c, and d are each amolar ratio of each siloxane unit, and when a sum (a+b+c+d) of the molarratios is converted into 1, a may be 0.2 to 0.8, 0.3 to 0.8, 0.3 to 0.7,or 0.3 to 0.6, b may be 0 to 0.5, 0 to 0.4, 0 to 0.3, or 0 to 0.2, c maybe 0 to 0.5, 0 to 0.4, 0 to 0.3, 0 to 0.2, or 0 to 0.1, and d may be 0.2to 0.8, 0.3 to 0.8, 0.3 to 0.7, or 0.3 to 0.6. In the average empiricalformula of Formula 1, d/(c+d) may be 0.3 or more, 0.5 or more, 0.7 ormore, 0.8 or more, or 0.85 or more. As a ratio of the Q unit of thepolyorganosiloxane (A) is controlled as described above, an excellentcrack resistance of the cured product may be maintained. The upper limitof the d/(c+d) is not particularly limited, and may be, for example, 1.

In Formula 1, e indicates an amount of a condensable functional groupincluded in the polyorganosiloxane (A), for example, a hydroxyl group oran alkoxy group. In Formula 1, e is 0 or a positive number, and forexample, in Formula 1, e/(c+d) may be present in the range of 0.2 orless, 0.15 or less, 0.1 or less, or 0.05 or less. By the control asdescribed above, compatibility between the components of the curablecomposition is maintained, and thereby a cured product having excellenttransparency may be formed after curing, and in addition, vaporresistance of the cured product may also be excellently maintained. Forexample, when the cured product is applied to a semiconductor device,long-term reliability of the device may also be ensured. The condensablefunctional group should not be present in the polyorganosiloxane (A), ifpossible, and therefore, the lower limit of e/(c+d) is not particularlylimited.

The polyorganosiloxane (A) may have a viscosity at 25° C. of 1,000 cP ormore or 2,000 cP or more, and thus processability before curing andhardness after curing may be suitably maintained.

The polyorganosiloxane (A) may have a weight average molecular weight(Mw) of 500 to 20,000 or 500 to 10,000. The term “weight averagemolecular weight” used herein may refer to a conversion value withrespect to standard polystyrene measured by gel permeationchromatography (GPC). Unless particularly defined otherwise, the term“molecular weight” may refer to a weight average molecular weight. Asthe molecular weight of the polyorganosiloxane (A) is controlled to 500or more, moldability before curing, or strength after curing may beeffectively maintained, and as the molecular weight of thepolyorganosiloxane (A) is controlled to 20,000 or 10,000 or less,viscosity may be maintained to a suitable level.

A method of preparing the polyorganosiloxane (A) is not particularlylimited, and a conventional method known in the art may be applied.

The curable composition may further include a polyorganosiloxaneincluding a hydrogen atom binding to a silicon atom (hereinafter,referred to as a polyorganosiloxane (B)). The polyorganosiloxane (B) mayhave, for example, one or at least two hydrogen atoms binding to asilicon atom. The polyorganosiloxane (B) may be, for example, ahigh-refractive-index polyorganosiloxane having an aryl group binding toa silicon atom. In addition, the polyorganosiloxane (B) may be a solidor liquid type. The polyorganosiloxane (B) may have a linear structure,that is, a structure composed of M and D units, or a structure includinga T or Q unit. Unless particularly limited, in a linear structure, asilicon atom may bind to a hydrogen atom at a terminal end of the linearstructure. Such a polyorganosiloxane (B) may have excellent reactivityto an aliphatic unsaturated bond included in the polyorganosiloxane (A).In addition, the polyorganosiloxane (B) may enhance crack resistance,and maintain gas permeability to a low level of a cured product. Thepolyorganosiloxane (B) maybe a low-molecular-weight or single molecularcompound. Accordingly, the polyorganosiloxane (B) may include 3 to 10, 3to 9, 3 to 8, 3 to 7, 3 to 6, or 3 to 5 silicon atoms.

The polyorganosiloxane (B) may be a crosslinking agent for crosslinkinga composition by a reaction of an aliphatic unsaturated bond present inthe polyorganosiloxane (A). For example, crosslinking and curing mayproceed by an addition-reaction of a hydrogen atom of thepolyorganosiloxane (B) and the aliphatic unsaturated bond of thepolyorganosiloxane (A), for example, an alkenyl group.

In the polyorganosiloxane (B), it is suitable that the hydrogen atombinds to the silicon (Si) atom present at the terminal end of the linearstructure, and may also be suitable that an amount of hydrogen atomsbinding to a silicon (Si) atom present in a repeating unit, not at theterminal end, is minimized. To ensure suitably reactivity, a molar ratio(H/Si) of the hydrogen (H) atom to the silicon (Si) atom in thepolyorganosiloxane (B) may be, for example, 1.0 or less, 0.9 or less,0.8 or less, or 0.75 or less. The molar ratio (H/Si) may also be 0.1 ormore, 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more.

The polyorganosiloxane (B) may be a high-refractive-indexpolyorganosiloxane, and a molar ratio (Ar/Si) of an aryl (Ar) groupbinding to the polyorganosiloxane (B) with respect to total silicon (Si)atoms may be, for example, approximately 0.25 or more, 0.3 or more, 0.3to 1.0, or 0.3 to 0.8. Within the above range, compatibility with othercomponents, a mechanical characteristic, and a gas permeability of thecurable composition may be excellently maintained.

The polyorganosiloxane (B) may be a solid or liquid type. When thepolyorganosiloxane (B) is a liquid type, a viscosity at 25° C. may be300 cP or less, or 200 cP or less. When the viscosity of thepolyorganosiloxane (B) is controlled as described above, it may beadvantageous in terms of processability or compatibility with othercomponents, but the present application is not limited to the aboverange. The polyorganosiloxane (B) may have a molecular weight of, forexample, less than 1,000 or less than 800. When the molecular weight ofthe polyorganosiloxane (B) is 1,000 or more, strength of the curedproduct may be probably degraded, and the compatibility with othercomponents may also be degraded. The lower limit of the molecular weightof the polyorganosiloxane (B) may be, but is not particularly limitedto, 250.

As the polyorganosiloxane (B), various kinds of compounds, for example,a compound of Formula 2 or 3, may be used.

In Formula 2, R is each independently a monovalent hydrocarbon group, atleast one R is an aryl group, and n is a number from 1 to 10. In Formula2, n may be, for example, 1 to 8, 1 to 6, 1 to 4, 1 to 3, or 1 to 2.

(HR¹ ₂SiO_(1/2))₃(R²SiO_(3/2))  [Formula 3]

In Formula 3, R¹ and R² are each independently hydrogen or a monovalenthydrocarbon group, and at least one of R¹ and R² is an aryl group.

A content of the polyorganosiloxane (B) may be selected in such a rangethat a molar ratio (H/Ak) of a hydrogen (H) atom binding to the siliconatom included in the polyorganosiloxane (B) with respect to an alkenyl(Ak) group included in the polyorganosiloxane (A) is, for example, 0.5to 3.0 or 0.7 to 2. As the hydrogen (H) atom binding to the silicon atomis mixed in the molar ratio (H/Ak), a composition exhibiting excellentprocessability and workability before curing, exhibiting excellent crackresistance, hardness, thermal impact resistance, and adhesive propertyafter curing, and not inducing whitening or surface stickiness may beprovided.

The curable composition may be a polyorganosiloxane including a hydrogenatom binding to a silicon atom, and further include, for example, apolymeric compound having a low refractive index. For example, thecurable composition may further include a polyorganosiloxane including ahydrogen atom binding to a silicon atom and 10 to 50 or 20 to 40 siliconatoms. The polyorganosiloxane may be a low-refractive-indexpolyorganosiloxane, and in this case, may have the above range of themolar ratio of the aryl group (Ar/Si). In another embodiment, the numberof the silicon atoms included in the polyorganosiloxane may be 25 ormore, 27 or more, or approximately 30 or more, and preferably,approximately 38 or less, or 36 or less. Such a compound is represented,for example, by Formula 2, and may include an aryl group of R which is amonovalent hydrocarbon group to satisfy the molar ratio (Ar/Si) of thearyl group of the low-refractive-index polyorganosiloxane. Here, n is inthe range from 18 to 38. In addition, in this case, n may be 23 or more,25 or more, or 28 or more, and preferably 36 or less or 34 or less. Arate of such a compound in the curable composition may be, but is notparticularly limited to, 5 to 30 parts by weight, 5 to 25 parts byweight, 5 to 20 parts by weight, or 5 to 15 parts by weight with respectto 100 parts by weight of the polyorganosiloxane (B). Unlessparticularly defined otherwise, the units “parts by weight” may be aweight ratio of each component to other components.

The curable composition may further include a compound having an averageempirical formula of Formula 4 (hereinafter, referred to as a compound(C)) as another compound including a hydrogen atom.

(HR₂SiO)_(a)(RSiO_(3/2))_(b)(R₂SiO_(2/2))_(c)  [Formula 4]

In Formula 4, R is each independently a monovalent hydrocarbon group, atleast one R is an aryl group, and when the sum (a+b+c) of a, b, and c isconverted into 1, a is 0.3 to 0.8, b is 0.2 to 0.7, and c is 0 to 0.5.

A ratio (H/Si) of a number of moles of hydrogen (H) atoms binding to asilicon atom with respect to a number of moles of total silicon (Si)atoms in the compound (C) may be, for example, approximately 0.2 to 1.0or 0.3 to 1.0.

The ratio (Ar/Si) of a number of moles of aryl (Ar) groups binding to asilicon atom with respect to a number of moles of total silicon (Si)atoms in the compound (C) may be, for example, 0 to 0.8. Another lowerlimit of the ratio (Ar/Si) may be, for example, 0.2, and another upperlimit thereof may be, for example, approximately 0.7.

When the compound (C) is used, the content may be suitably selected inconsideration of, for example, the ratio of the polyorganosiloxane (B)or an amount of the aliphatic unsaturated bond.

The curable composition may further include another compound including ahydrogen atom, for example, a compound of Formula 5 (hereinafter,referred to as a compound (D)).

R₃SiO(HRSiO)_(r)(R₂SiO)_(s)OSiR₃  [Formula 5]

In Formula 5, R is each independently hydrogen, an epoxy group, or amonovalent hydrocarbon group, r is a number from 5 to 100, and s is anumber from 0 to 100 or 5 to 100. In Formula 5, the monovalenthydrocarbon group may be, for example, a monovalent hydrocarbon groupexcluding an aryl group.

A ratio (H/Si) of a number of moles of hydrogen (H) atoms binding to asilicon atom with respect to a number of moles of total silicon (Si)atoms included in the compound (D) may be 0.2 to 1 or 0.3 to 1.Curability may be excellently maintained by controlling the molar ratio(H/Si) as described above. In addition, the compound (D) may have aviscosity at 25° C. of 0.1 cP to 100,000 cP, 0.1 cP to 10,000 cP, 0.1 cPto 1,000 cP, or 0.1 cP to 300 cP. When the compound (D) has theviscosity in the above range, processability of the composition andhardness of the cured product may be excellently maintained.

The ratio (Ar/Si) of a number of moles of aryl (Ar) groups binding to asilicon atom with respect to a number of moles of total silicon (Si)atoms in the compound (D) may be, for example, approximately 0 to 0.8 or0 to 0.7.

A content of the compound (D) may be suitably controlled inconsideration of an amount of total functional groups containing analiphatic unsaturated bond included in the curable composition, forexample, the amount of the alkenyl groups included in thepolyorganosiloxane (A) and the amount of hydrogen atoms binding to asilicon atom included in the polyorganosiloxane (B).

The curable composition may further include a compound including analiphatic unsaturated bond, for example, a linear orpartially-crosslinked polyorganosiloxane (hereinafter, referred to as apolyorganosiloxane (E)). The term “linear polyorganosiloxane” usedherein may be a polyorganosiloxane composed of M and D units, and theterm “partially-crosslinked polyorganosiloxane” is a polyorganosiloxanewhich has a sufficiently long linear structure derived from the D unit,and to which a T or Q unit, for example, a T unit is partiallyintroduced. For example, the polyorganosiloxane may have a ratio(D/(D+T+Q)) of the D unit with respect to the sum of the D, T, and Qunits included therein of 0.7 or more, 0.75 or more, 0.8 or more, or0.85 or more. The ratio (D/(D+T+Q)) may also be less than 1 orapproximately 0.95 or less.

The polyorganosiloxane (E) may be a low-refractive-indexpolyorganosiloxane or a high-refractive-index polyorganosiloxane.

The polyorganosiloxane (E) may include at least one aliphaticunsaturated bond, for example, alkenyl group. For example, thepolyorganosiloxane (E) may include the functional group in such anamount that a molar ratio (Ak/Si) of a functional group (Ak) includingthe aliphatic unsaturated bond, for example, an alkenyl group withrespect to total silicon (Si) atoms included in the polyorganosiloxane(E) is 0.001 to 0.3. The molar ratio (Ak/Si) may be, in anotherembodiment, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or0.05 or more. In addition, the molar ratio (Ak/Si) may be, in anotherembodiment, 0.25 or less or 0.2 or less. By such control, curability ofa curable composition may be maintained in a suitable range, aphenomenon of leaking an unreacted component from a surface of a curedproduct after curing may be prevented, and excellent crack resistancemay be maintained.

The polyorganosiloxane (E) may be a low-refractive-indexpolyorganosiloxane or a high-refractive-index polyorganosiloxane. Forexample, when the polyorganosiloxane (E) is a low-refractive-indexpolyorganosiloxane, excellent high temperature thermal resistance of thecured product may be maintained, and compatibility with anothercomponent may be increased.

The polyorganosiloxane (E) may have, for example, an average empiricalformula of Formula 6.

(R¹ ₃SiO_(1/2))_(a)(R² ₂SiO_(2/2))_(b)(R³₁SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula 6]

In Formula 6, R¹ to R³ are each independently an epoxy group or amonovalent hydrocarbon group, one or at least two of R¹ to R³ arealkenyl groups, a, c, and d are each independently 0 or a positivenumber, and b is a positive number.

When the polyorganosiloxane (E) is a low-refractive-index compound, themonovalent hydrocarbon group may be a monovalent hydrocarbon groupexcluding an aryl group.

In Formula 6, one or at least two of R¹ to R³ are alkenyl groups, andfor example, an alkenyl group may be present within a range satisfyingthe above-described molar ratio (Ak/Si). Unless particularly limited,for example, the alkenyl group may be presented at the position of R³.

In the average empirical formula of Formula 6, a, b, c, and d representmolar ratios of respective siloxane units of the polyorganosiloxane (E).When the sum (a+b+c+d) is converted into 1, a may be 0.001 to 0.2, 0.01to 0.2, 0.02 to 0.2, 0.03 to 0.2, 0.04 to 0.2, or 0.04 to 0.1, b may be0.7 to 0.999 or 0.7 to 0.95, c may be 0 to 0.3, more than 0 to 0.2 orless, or more than 0 to 0.1 or less, and d may be 0 to 0.3, 0 to 0.2, or0 to 0.1.

In Formula 6, each siloxane unit may be present such that, for example,(c+d)/(a+b+c+d) is 0 to 0.3, 0 to 0.2, or 0 to 0.1. In addition, whenthe polyorganosiloxane (E) is partially crosslinked, in Formula 6,b/(b+c+d) may be more than 0.7, and less than 1. In another embodimentof the partial crosslink, b/(b+c+d) may be 0.7 to 0.97 or 0.65 to 0.97.As a ratio of the siloxane unit is controlled as described above,suitable physical properties may be ensured according to use orapplication.

The polyorganosiloxane (E) may be included in, for example, aring-opening polymerization product of a mixture including a cyclicpolyorganosiloxane. The reaction product includes a cyclic compound, forexample, having a weight average molecular weight (Mw) of 800 or less,750 or less, or 700 or less, for example, a cyclic polyorganosiloxane,whose ratio may be 7 wt % or less, 5 wt % or less, or 3 wt % or less.The lower limit of the ratio of the cyclic compound may be, for example,0 wt % or 1 wt %. By the control within the above range, a cured producthaving excellent long-term reliability and crack resistance may beprovided.

The polyorganosiloxane (E) or a reaction product including the same hasan area of a peak derived from an alkoxy group binding to a silicon atomwith respect to an area of a peak derived from an aliphatic unsaturatedbond-containing functional group binding to a silicon, for example, analkenyl group such as a vinyl group of 0.01 or less, 0.005 or less, or 0in a spectrum obtained by ¹H NMR. Within the range, a suitable viscositycharacteristic may be exhibited, and other physical properties mayexcellently be maintained.

The polyorganosiloxane (E) or a reaction product including the same mayhave an acid value calculated by KOH titration of 0.02 or less, 0.01 orless, or 0. In this range, a suitable viscosity characteristic may beexhibited, and other physical properties may excellently be maintained.

The polyorganosiloxane (E) or a reaction product including the same mayhave a viscosity at 25° C. of 500 cP or more, 1,000 cP or more, 2,000 cPor more, or 5,000 cP or more. In this range, suitable processability andhardness may be maintained. The upper limit of the viscosity is notparticularly limited, but the viscosity may be, for example, 500,000 cPor less, 400,000 cP or less, 300,000 cP or less, 200,000 cP or less,100,000 cP or less, 80,000 cP or less, 70,000 cP or less, or 65,000 cPor less.

The polyorganosiloxane (E) or a reaction product including the same mayhave a molecular weight of 500 to 100,000 or 1,500 to 50,000. In thisrange, suitable moldability, hardness, and strength may be maintained.

A polymerization product including the polyorganosiloxane (E) may be,for example, a ring-opening polymerization product of a mixtureincluding a cyclic polyorganosiloxane. When the polyorganosiloxane (E)has a partially-crosslinked structure, the mixture may further include,for example, a cage structure or a partial cage structure, or apolyorganosiloxane including a T unit. As the cyclic polyorganosiloxanecompound, for example, a compound represented by Formula 7 may be used.

In Formula 7, R^(d) and R^(e) may be each independently an epoxy groupor a monovalent hydrocarbon group, and o is 3 to 6.

The cyclic polyorganosiloxane may also include a compound of Formula 8and a compound of Formula 9.

In Formulas 8 and 9, R^(f) and R^(g) are an epoxy group or an alkylgroup, R^(h) and R^(i) are an epoxy group or a monovalent hydrocarbongroup, p is a number from 3 to 6, and q is a number from 3 to 6.

In Formulas 7 to 9, specific kinds of R^(f) to R^(i), particular valuesof o, p, and q, and a ratio of each component in the mixture may bedetermined by a desired structure of the polyorganosiloxane (E).

When the polyorganosiloxane (E) has a partially-crosslinked structure,the mixture may include a compound having an average empirical formulaof Formula 9 or a partial cage structure, or may further include acompound having an average empirical formula of Formula 10 as thepolyorganosiloxane including a T unit.

[R^(j)SiO_(3/2)]  [Formula 10]

[R^(k)R^(l) ₂SiO_(1/2)]_(p)[R^(m)SiO_(3/2)]_(q)  [Formula 11]

In Formulas 10 and 11, R^(j), R^(k), and R^(m) are each independently anepoxy group or a monovalent hydrocarbon group, R^(l) is an epoxy groupor an alkyl group having 1 to 4 carbon atoms, p is a number from 1 to 3,and q is a number from 1 to 10.

In Formulas 10 and 11, specific kinds of R^(j) to R^(m), particularvalues of p and q, and a ratio of each component in the mixture may bedetermined by a desired structure of the polyorganosiloxane (E).

When the cyclic polyorganosiloxane has a cage structure and/or a partialcage structure, or reacts with a polyorganosiloxane including a T unit,a desired polyorganosiloxane having a partially-crosslinked structuremay be synthesized in a sufficient molecular weight. In addition,according to the above method, a desired product having excellentphysical properties may be prepared by minimizing a functional grouphaving an alkoxy group or a hydroxyl group binding to a silicon atom inthe polyorganosiloxane or a polymerization product including the same.

In one embodiment, the mixture may further include a compoundrepresented by Formula 12.

(R^(n)R^(o) ₂Si)₂O  [Formula 12]

In Formula 12, R^(n) and R^(o) are an epoxy group or a monovalenthydrocarbon group.

In Formula 12, a specific kind of the monovalent hydrocarbon group or ablending ratio in the mixture may be determined according to a desiredpolyorganosiloxane (E).

A reaction of each component in the mixture may be performed in thepresence of a suitable catalyst. Accordingly, the mixture may furtherinclude a catalyst.

A catalyst which may be included in the mixture may be, for example, abase catalyst. A suitable base catalyst may be, but is not limited to, ametal hydroxide such as KOH, NaOH, or CsOH; a metal silanolate includingan alkali metal compound and a siloxane; or a quaternary ammoniumcompound such as tetramethylammonium hydroxide, tetraethylammoniumhydroxide, or tetrapropylammonium hydroxide.

A ratio of the catalyst in the mixture may be suitably selected inconsideration of desired reactivity, and may be, for example, 0.01 to 30parts by weight or 0.03 to 5 parts by weight with respect to 100 partsby weight of a total weight of a reaction product in the mixture.

In one embodiment, a reaction of the mixture may be performed in theabsence of a solvent or the presence of a suitable solvent. Any kind ofa solvent may be used as long as a reaction product in the mixture, thatis, disiloxane or polysiloxane, may be suitably mixed with the catalyst,and it does not have a significant influence on reactivity. The solventmay be, but is not limited to, an aliphatic hydrocarbon-based solventsuch as n-pentane, i-pentane, n-hexane, i-hexane, 2,2,4-trimethylpentane, cyclohexane, or methylcyclohexane; an aromatic solvent such asbenzene, toluene, xylene, trimethyl benzene, ethyl benzene, ormethylethyl benzene; a ketone-based solvent such as methylethylketone,methylisobutylketone, diethylketone, methyl n-propyl ketone, methyln-butyl ketone, cyclohexanone, methylcyclohexanone, or acetylacetone; anether-based solvent such as tetrahydrofuran, 2-methyl tetrahydrofuran,ethyl ether, n-propyl ether, isopropyl ether, diglyme, dioxine,dimethyldioxane, ethyleneglycol monomethyl ether, ethyleneglycoldimethyl ether, ethyleneglycol diethyl ether, propyleneglycol monomethylether, or propyleneglycol dimethyl ether; an ester-based solvent such asdiethyl carbonate, methyl acetate, ethyl acetate, ethyl lactate,ethyleneglycol monomethyl ether acetate, propyleneglycol monomethylether acetate, or ethyleneglycol diacetate; or an amide-based solventsuch as N-methyl pyrrolidone, formamide, N-methyl formamide, N-ethylformamide, N,N-dimethyl acetamide, or N,N-diethylacetamide.

The reaction of the mixture, for example, a ring opening polymerizationreaction, may be performed by adding the catalyst to the reactionproduct at a reaction temperature of, for example, 0 to 150° C. or 30 to130° C. In addition, a reaction time may be controlled within a rangeof, for example, 1 hour to 3 days.

The curable composition may further include a hydrosilylation catalyst.The hydrosilylation catalyst may be used to stimulate a hydrosilylationreaction. As the hydrosilylation catalyst, all of conventionalcomponents known in the art may be used. As such a catalyst, aplatinum-, palladium-, or rhodium-based catalyst may be used. In thespecification, a platinum-based catalyst may be used in consideration ofcatalyst efficiency, and may be, but is not limited to, chloroplatinicacid, platinum tetrachloride, an olefin complex of platinum, an alkenylsiloxane complex of platinum, or a carbonyl complex of platinum.

A content of the hydrosilylation catalyst is not particularly limited aslong as the hydrosilylation catalyst is included at a catalytic amount,that is, an amount capable of serving as a catalyst. Conventionally, thehydrosilylation catalyst may be used at 0.1 to 200 ppm, and preferably0.2 to 100 ppm based on an atomic weight of platinum, palladium, orrhodium.

The curable composition may further include a tackifier in terms offurther enhancement in adhesive property to various kinds of substrates.The tackifier is a component capable of improving a self-adhesiveproperty to the composition or cured product, and may improve aself-adhesive property particularly to a metal and an organic resin.

The tackifier may be, but is not limited to, a silane having at leastone or two functional groups selected from the group consisting of analkenyl group such as a vinyl group, a (meth)acryloyloxy group, ahydrosilyl (SiH) group, an epoxy group, an alkoxy group, an alkoxysilylgroup, a carbonyl group, and a phenyl group; or an organic siliconcompound such as a cyclic or linear siloxane having 2 to 30 or 4 to 20silicon atoms. In the specification, one or at least two of thetackifiers may be additionally mixed.

In one embodiment, as the tackifier, a polyorganosiloxane which includesan alkenyl group and an epoxy group binding to a silicon atom, and has amolar ratio (Ak/Si) of an alkenyl (Ak) group to total silicon (Si) atomsin a range of 0.02 to 0.5, 0.08 to 0.5, 0.1 to 0.5, or 0.1 to 0.4, amolar ratio (Ar/Si) of an aryl (Ar) group to total silicon (Si) atoms ina range of 0.45 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 orless, or 0.05 or less, and a molar ratio (Ep/Si) of an epoxy (Ep) groupto total silicon (Si) atoms in a range of 0.01 to 0.5, 0.05 to 0.5, 0.1to 0.5, or 0.1 to 0.45, may be used.

For example, the tackifier may have an average empirical formula ofFormula 13.

(R¹ ₃SiO_(1/2))_(a)(R²₂SiO_(2/2))_(b)(R³SiO_(3/2))_(c)(SiO_(4/2))_(d)(OR)_(e)  [Formula 13]

In Formula 13, R and R¹ to R³ may be each independently a monovalenthydrocarbon group or an epoxy group, at least one of R¹ to R³ may be analkenyl group or an epoxy group, each of a, b, c, d, and e may be 0 or apositive number, c/(c+d) may be 0.3 or more, and e/(c+d) may be 0.2 orless. However, here, at least one of c and d may be a positive number.

When the tackifier is a low-refractive-index component not substantiallyincluding an aryl group, each of the R and R¹ to R³ may be the abovesubstituent excluding an aryl group. When the tackifier is alow-refractive-index component, in Formula 13, an aryl group may beincluded to have the above-described molar ratio (Ar/Si) of the arylgroup of 0.3 or less, 0.2 or less, or 0.15 or less, or substantially 0.

In Formula 13, one or at least two of R¹ to R³ may be an alkenyl group.In one embodiment, in Formula 13, the alkenyl group may be included tosatisfy the above-described molar ratio (Ak/Si). In addition, in Formula13, at least one of R¹ to R³ may be an epoxy group. In one embodiment,in Formula 13, the epoxy group may be included to satisfy theabove-described molar ratio (Ep/Si).

In the average empirical formula of Formula 13, a, b, c, and d are molarratios of siloxane units, and when the sum (a+b+c+d) is converted into1, a may be 0.2 to 0.8, 0.3 to 0.8, 0.3 to 0.7, or 0.3 to 0.6, b may be0 to 0.5, 0 to 0.4, 0 to 0.3, or 0 to 0.2, c may be 0 to 0.8, 0.1 to0.7, 0.1 to 0.65, 0.1 to 0.6, or 0.1 to 0.5, and d may be 0 to 0.5, 0 to0.4, 0 to 0.3, or 0 to 0.2. In the average empirical formula of Formula13, c/(c+d) may be 0.3 or more, 0.5 or more, 0.65 or more, or 0.7 ormore. As the molar ratios of the siloxane units of the tackifier arecontrolled as described above, a semiconductor device maintaining anexcellent adhesive property of a cured product and having excellentreliability may be provided. The upper limit of the c/(c+d) may be, butis not particularly limited to, for example, 1, 0.9, 0.8, or 0.75.

In Formula 13, e indicates an amount of a condensable functional groupincluded in the polyorganosiloxane, for example, a hydroxyl group or analkoxy group. In Formula 1, e is 0 or a positive number, and forexample, in Formula 13, e/(c+d) may be presented in a range to be 0.2 orless, 0.15 or less, 0.1 or less, or 0.05 or less. As compatibilitybetween components of the curable composition is maintained through suchcontrol, a cured product having excellent transparency after curing maybe formed. In addition, excellent vapor resistance of the cured productmay be maintained, and when the cured product is applied to, forexample, a semiconductor device, long-term reliability of the device mayalso be ensured. In the polyorganosiloxane, the condensable functionalgroup should not be present if possible, and thus the lower limit of thee/(c+d) is not particularly limited.

Such a tackifier may have, for example, a molecular weight of 500 to20,000 or 500 to 10,000.

For example, the tackifier may be included in a ratio of 0.1 to 20 partsby weight with respect to 100 parts by weight of a solid content of thecurable composition, but the content may be suitably changed inconsideration of desired improvement in adhesive property.

The curable composition may further include one or at least two ofadditives including a reaction inhibitor such as 2-methyl-3-butyne-2-ol,2-phenyl-3-1-butyne-2-ol, 3-methyl-3-penten-1-yne,3,5-dimethyl-3-hexen-1-yne,1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, orethynylcyclohexane; an inorganic filler such as silica, alumina,zirconia, or titania; a carbon-functional silane having an epoxy groupand/or alkoxysilyl group, a partial hydrolysis-condensation productthereof or a siloxane compound; a thixotropic agent such as a haze-phasesilica that can be used in combination with polyether; a filler; aphosphor; a conductivity providing agent such as metal powder of silver,copper, or aluminum or various carbon materials; or a color adjustingagent such as a pigment or dye as needed.

Another aspect of the present application provides a semiconductordevice, for example, an optical semiconductor device. The illustrativesemiconductor device may be encapsulated with an encapsulant including acured product of the curable composition. Examples of the semiconductordevice encapsulated with an encapsulant include a diode, a transistor, athyristor, a photocoupler, a CCD, a solid-phase image pick-up diode, amonolithic IC, a hybrid IC, an LSI, a VLSI or a light-emitting diode(LED). In one embodiment, the semiconductor device may be an LED.

The LED may be one formed by stacking a semiconductor material on asubstrate. The semiconductor material may be, but is not limited to,GaAs, GaP, GaAlAs, GaAsP, AlGaInP, GaN, InN, AlN, InGaAlN, or SiC. Inaddition, as the substrate, a sapphire, spinel, SiC, Si, ZnO, or GaNsingle crystal may be used.

In addition, to prepare the LED, when necessary, a buffer layer may beformed between a substrate and a semiconductor material. As the bufferlayer, GaN or AlN may be used. A method of stacking a semiconductormaterial on a substrate may be, but is not particularly limited to,MOCVD, HDVPE, or liquid growth. In addition, a structure of the LED maybe, for example, a mono junction including an MIS junction, a PNjunction, and a PIN junction, a hetero junction, or a double heterojunction. In addition, the LED may be formed using a mono or multiplequantum well structure.

In one embodiment, an emission wavelength of the LED may be, forexample, 250 to 550 nm, 300 to 500 nm, or 330 to 470 nm. The emissionwavelength may refer to a main emission peak wavelength. As the emissionwavelength of the LED is set in the above range, a white LED having alonger life span, high energy efficiency, and high color expression maybe obtained.

The LED may be encapsulated using the composition. In addition, theencapsulation of the LED may be performed only using the composition,and in some cases, another encapsulant may be used in combination withthe composition. When two kinds of encapsulants are used in combination,after the encapsulation using the composition, the encapsulated LED mayalso be encapsulated with another encapsulant, or the LED may beencapsulated with another encapsulant and then encapsulated again withthe composition. As another encapsulant, an epoxy resin, a siliconresin, an acryl resin, a urea resin, an imide resin, or glass may beused.

To encapsulate the LED with the curable composition, for example, amethod including previously injecting the composition into a mold,dipping a lead frame to which the LED is fixed therein and curing thecomposition, or a method including injecting the composition into a moldinto which the LED is inserted and curing the composition may be used.As a method of injecting the composition, injection by a dispenser,transfer molding, or injection molding may be used. In addition, asother encapsulating methods, a method of dropping the composition on theLED, coating the composition by screen printing or using a mask, andcuring the composition, and a method of injecting the composition into acup in which the LED is disposed on a bottom by a dispenser and curingthe composition may be included.

In addition, the curable composition may be used as a diamond materialfixing the LED to a lead terminal or package, or a passivation layer orpackage substrate on the LED as needed.

When it is necessary to cure the composition, the curing may beperformed by maintaining the composition, for example, at a temperatureof 60 to 200° C. for 10 minutes to 5 hours, or in at least two steps ata suitable temperature and for a suitable time, but the presentapplication is not limited thereto.

A shape of the encapsulant is not particularly limited, and for example,may be a bullet-type lens, planar, or thin film shape.

In addition, additional enhancement of performance of the LED may bepromoted according to the conventional method known in the art. Toenhance performance, for example, a method of disposing a reflectivelayer or light collecting layer on a back surface of the LED, a methodof forming a complementary coloring part on its bottom, a method ofdisposing a layer absorbing light having a shorter wavelength than themain emission peak on the LED, a method of encapsulating the LED andfurther molding the LED with a hard material, a method of inserting theLED into a through hole to be fixed, or a method of contacting the LEDwith a lead member by flip-chip contact to extract light from adirection of the substrate, may be used.

The optical semiconductor device, for example, the LED may beeffectively applied to, for example, backlights for liquid crystaldisplays (LCDs), lights, various kinds of sensors, light sources of aprinter and a copy machine, light sources for an automobile gauge,signal lights, pilot lights, display devices, light sources of planarLEDs, displays, decorations, or various kinds of lights.

Effect

An illustrative curable composition can provide a cured product havingexcellent processability, workability, and adhesive property, and notinducing whitening and surface stickiness. The curable composition canalso provide a cured product having excellent transparency, vaporresistance, mechanical characteristics, and crack resistance, andtherefore, can exhibit excellent long-term reliability when beingapplied to various electronic parts.

ILLUSTRATIVE EMBODIMENTS

Hereinafter, a curable composition will be described in further detailwith reference to Examples and Comparative Examples, but the range ofthe curable composition is not limited to the following Examples. In thespecification, the abbreviations “Vi,” “Ph,” “Me,” and “Ep” refer to avinyl group, a phenyl group, a methyl group, and a 3-glycidoxypropylgroup, respectively.

1. Evaluation of Characteristics of Device

Characteristics of a device were evaluated using a 5630 LED packagemanufactured of polyphthalamide (PPA). A curable composition prepared ina PPA cup was dispensed, and then cured by being maintained at 60° C.for 1 hour, at 80° C. for 1 hour, and then at 150° C. for 4 hours,thereby manufacturing a surface-mounting LED. Afterward, themanufactured LED was operated for 800 hours while being maintained at85° C. with a current of 100 mA. Subsequently, a ratio of reduction inbrightness after operation with respect to initial brightness wasmeasured, and evaluated according to the following criteria.

<Evaluation Criteria>

A: when the ratio of reduction in brightness with respect to initialbrightness was 5% or less

B: when the ratio of reduction in brightness with respect to initialbrightness was more than 5% and 7% or less

C: when the ratio of reduction in brightness with respect to initialbrightness was more than 7%

2. Evaluation of High Temperature Thermal Resistance

High temperature thermal resistance was evaluated according to thefollowing criteria by injecting a curable composition between two glassplates spaced 1 mm apart from each other, curing the composition at 60°C. for 1 hour, at 80° C. for 1 hour, and then at 150° C. for 4 hours,maintaining the cured product at 200° C. for 24 hours, and measuring aratio of reduction in light transmittance with respect to initial lighttransmittance using a UV-Vis spectrometer. Here, the light transmittancewas an average value of light transmittance at a wavelength of 400 nm to450 nm.

<Evaluation Criteria>

A: when a ratio of reduction in light transmittance with respect toinitial light transmittance was 5% or less

B: when a ratio of reduction in light transmittance with respect toinitial light transmittance was more than 5% and 7% or less

C: when a ratio of reduction in light transmittance with respect toinitial light transmittance was more than 7%

Example 1

A curable composition was prepared by preparing a mixture (blendingamounts: Formula A: 15 g, Formula B: 100 g, Formula C: 21 g, and FormulaD: 1.0 g) by mixing compounds represented by Formulas A to D prepared byknown methods, and blending a catalyst(platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane) to have acontent of Pt(0) of 2 ppm.

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₃₀  [Formula A]

(ViMe₂SiO_(1/2))(Me₃SiO_(1/2))₄(SiO_(4/2))₅  [Formula B]

(HMe₂SiO_(1/2))₂(MePhSiO_(2/2))  [Formula C]

(ViMe₂SiO_(1/2))₂(Me₃SiO_(1/2))₂(EpSiO_(3/2))_(2.5)(SiO_(4/2))  [FormulaD]

Example 2

A curable composition was prepared by the same method as described inExample 1, except that 26 g of a compound of Formula E was mixed,instead of the compound of Formula C.

(HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))  [Formula E]

Example 3

A curable composition was prepared by the same method as described inExample 1, except that 20 g of the compound of Formula E and 2 g of acompound of Formula F were blended, instead of the compound of FormulaC.

(HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))  [Formula E]

(ViMe₂SiO_(1/2))₂(HMeSiO_(2/2))₃₀  [Formula F]

Example 4

A curable composition was prepared by the same method as described inExample 2, except that 13 g of a compound of Formula G was blended,instead of the compound of Formula A.

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₂₀(Ph₂SiO_(2/2))₂  [Formula G]

Example 5

A curable composition was prepared under the same conditions asdescribed in Example 2, except that 5.5 g of a compound of Formula H wasblended, instead of the compound of Formula A.

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₂₀(ViSiO_(3/2))₂  [Formula H]

Example 6

A curable composition was prepared under the same conditions asdescribed in Example 2, except that 11 g of a compound of Formula I wasblended, instead of the compound of Formula A.

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₂₀(SiO_(4/2))₂  [Formula I]

Example 7

A curable composition was prepared under the same conditions asdescribed in Example 2, except that 11 g of a compound of Formula J wasblended, instead of the compound of Formula A.

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₂₀(MeSiO_(3/2))₂  [Formula J]

Example 8

A curable composition was prepared under the same conditions asdescribed in Example 2, except that 111 g of a compound of Formula K wasblended, instead of the compound of Formula B.

(ViMe₂SiO_(1/2))₁(Me₃SiO_(1/2))₄(SiO_(4/2))₅(PhSiO_(3/2))_(0.5)  [FormulaK]

Example 9

A curable composition was prepared by mixing a compound of Formula Lrespectively prepared by known methods with the compounds of Formulas Cand D (blending amounts: Formula L: 100 g, Formula C: 18.5 g, Formula D:1.0 g), and blending a catalyst by the same method as described inExample 1.

(ViMe₂SiO_(1/2))(Me₃SiO_(1/2))₄(Me₂SiO_(2/2))_(1.5)(SiO_(4/2))₅  [FormulaL]

Comparative Example 1

A curable composition was prepared by the same method as described inExample 1, except that 6.5 g of the compound of Formula F was blended,instead of the compound of Formula C.

Comparative Example 2

A curable composition was prepared by mixing compounds of Formulas M, N,and O respectively prepared by known methods with the compound ofFormula E (blending amounts: Formula M: 40 g, Formula N: 100 g, FormulaE: 51.5 g, Formula O: 1.5 g), and blending a catalyst by the same methodas described in Example 1.

(ViMe₂SiO_(1/2))₂(MePhSiO_(2/2))₄₀  [Formula M]

(ViMe₂SiO_(1/2))₂(MePhSiO_(3/2))_(0.3)(PhSiO_(3/2))_(3.5)  [Formula N]

(ViMe₂SiO_(1/2))₂(EpSiO_(3/2))₃(MePhSiO_(2/2))₂₀  [Formula O]

Comparative Example 3

A curable composition was prepared by the same method as described inExample 1, except that 31 g of a compound of Formula Q was blended,instead of the compound of Formula C.

(HMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₃  [Formula Q]

Comparative Example 4

A curable composition was prepared by the same method as described inExample 1, except that 340 g of a compound of Formula R was blended,instead of the compound of Formula C.

(HMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₅₀  [Formula R]

Physical properties measured with respect to the Examples andComparative Examples are summarized and listed in Table 1.

TABLE 1 Reliability High temperature of device thermal resistanceExample 1 A A Example 2 A A Example 3 A A Example 4 A A Example 5 A AExample 6 A A Example 7 A A Example 8 A A Example 9 A A Comparative C AExample 1 Comparative A C Example 2 Comparative C A Example 3Comparative C A Example 4

What is claimed is:
 1. A curable composition, comprising: (A) apolyorganosiloxane having an aliphatic unsaturated bond, and a molarratio (Ar/Si) of an aryl (Ar) group to a silicon (Si) atom of 0.2 orless; and (B) a polyorganosiloxane including a hydrogen atom and an arylgroup, which bind to a silicon atom, having a molar ratio of an aryl(Ar) group to a silicon (Si) atom of 0.25 or more, and having 3 to 10silicon atoms.
 2. The curable composition according to claim 1, whereinthe molar ratio (Ar/Si) of an aryl (Ar) group to a silicon (Si) atom is0.15 or less.
 3. The curable composition according to claim 1, whereinthe polyorganosiloxane (A) has an average empirical formula of Formula1:(R¹ ₃SiO_(1/2))_(a)(R²₂SiO_(2/2))_(b)(R³SiO_(3/2))_(c)(SiO_(4/2))_(d)(OR)_(e)  [Formula 1]where R and R¹ to R³ are each independently a monovalent hydrocarbongroup, at least one of R¹ to R³ is an alkenyl group, each of a, b, c,and d is 0 or a positive number, d/(c+d) is 0.3 or more, and e/(c+d) is0.2 or less.
 4. The curable composition according to claim 1, whereinthe polyorganosiloxane (A) has a molar ratio (Ak/Si) of an alkenyl (Ak)group to a silicon (Si) atom of 0.02 to 0.5.
 5. The curable compositionaccording to claim 1, wherein the polyorganosiloxane (A) has a weightaverage molecular weight of 500 to 20,000.
 6. The curable compositionaccording to claim 1, wherein the polyorganosiloxane (B) has a molecularweight of less than 1,000.
 7. The curable composition according to claim1, wherein the polyorganosiloxane (B) is a compound of Formula 2 or acompound of Formula 3:

(HR¹ ₂SiO_(1/2))₃(R²SiO_(3/2))  [Formula 3] where R, R¹, and R² are eachindependently hydrogen or a monovalent hydrocarbon group, at least one Ris an aryl group, at least one of R¹ and R² is an aryl group, and n is anumber from 1 to
 10. 8. The curable composition according to claim 1,further comprising a polyorganosiloxane including a hydrogen atombinding to a silicon atom, having a molar ratio of an aryl (Ar) group toa silicon (Si) atom of 0.3 or less, and including 10 to 50 siliconatoms.
 9. The curable composition according to claim 1, furthercomprising a compound of an average empirical formula of Formula 4:(HR₂SiO_(1/2))_(a)(RSiO_(3/2))_(b)(R₂SiO_(2/2))_(c)  [Formula 4] where Ris each independently a monovalent hydrocarbon group, at least one R isan aryl group, and when the sum (a+b+c) of a, b, and c is converted into1, a is 0.3 to 0.8, b is 0.2 to 0.7, and c is 0 to 0.5.
 10. The curablecomposition according to claim 1, further comprising a compound ofFormula 5:R₃SiO(HRSiO)_(r)(R₂SiO)_(s)OSiR₃  [Formula 5] where R is eachindependently hydrogen, an epoxy group, or a monovalent hydrocarbongroup, r is a number from 5 to 100, and s is a number from 0 to
 100. 11.The curable composition according to claim 1, further comprising alinear polyorganosiloxane or a crosslinked polyorganosiloxane having amolar ratio (D/(D+T+Q)) of total bifunctional siloxane units (D) withrespect to a bifunctional siloxane unit (D), a trifunctional siloxaneunit (T), and a tetrafunctional siloxane unit (Q) of 0.7 or more. 12.The curable composition according to claim 11, wherein the linear orcrosslinked polyorganosiloxane has a molar ratio (Ar/Si) of an aryl (Ar)group to a silicon (Si) atom of 0.3 or less.
 13. The curable compositionaccording to claim 11, wherein the linear or crosslinkedpolyorganosiloxane has an average empirical formula of Formula 6:(R³SiO_(1/2))_(a)(R²SiO_(2/2))_(b)(R¹SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula6] where R¹ to R³ are each independently an epoxy group or a monovalenthydrocarbon group, one or at least two of R¹ to R³ are an alkenyl group,a, c, and d are each independently 0 or a positive number, and b is apositive number.
 14. The curable composition according to claim 1,further comprising a polyorganosiloxane, which includes an alkenyl groupand an epoxy group binding to a silicon atom, and has a molar ratio(Ak/Si) of an alkenyl (Ak) group to total silicon (Si) atoms of 0.02 to0.5, a molar ratio (Ar/Si) of an aryl (Ar) group to total silicon (Si)atoms of 0.45 or less, and a molar ratio (Ep/Si) of an epoxy (Ep) groupto total silicon (Si) atoms of 0.01 to 0.5.
 15. A semiconductor deviceencapsulated with an encapsulant including a cured product of thecurable composition of claim
 1. 16. An optical semiconductor deviceencapsulated with an encapsulant including a cured product of thecurable composition of claim
 1. 17. A liquid crystal display devicecomprising the optical semiconductor device of claim
 16. 18. A lightingapparatus comprising the optical semiconductor device of claim 16.